All Dielectric High Q-Factor Metasurface Refractive Index Sensor Based on Dual Fano Resonances in THz Region
Pooja Agarwal, Kamal Kishor, Ravindra Kumar Sinha
Abstract
In this paper, we propose an all-dielectric metasurface refractive index sensor driven by dual Fano resonances. The proposed sensor exhibits remarkable characteristics, including high sensitivity, large quality factor (Q), and significant figure of merit (FOM) simultaneously. The transmission spectra and field profile of the designed metasurface have been evaluated in order to do the analysis of Fano resonance. The Q-factor for the corresponding resonance mode <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = 1.79 THz and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = 3.90 THz are 920.00 and 685.53 respectively. It is also reported that the transmission properties are very sensitive to the surrounding refractive index. The FOM of the proposed device are 514.40/RIU and 351.55/RIU, and its sensitivity are 1000 GHz/RIU and 2000 GHz/RIU, respectively for the resonant frequency <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . It is noteworthy that by adjusting the thickness of the Si-bars ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), the Q factor for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -mode can be tune from 685.53 to 4409.00. This showcases the versatility of the proposed design, making it a promising tool for various sensing applications.